In the past, it has been common to manufacture mattress covers by sewing an envelope-like cover, and then fitting the cover, over the mattress interior, including internal padding components, through a zipper closure. This type of cover is of particular use in hospitals and similar institutional settings in which many people are housed and cared for by a separate staff. The envelope-like construction of the mattress cover saves cost of replacing internal padding components by just replacing cover.
In this prior art type mattress cover, the cover itself is frequently formed by stitching the top and bottom sections of the envelope-like cover together, and by providing a fastener such as a zipper in the place of a stitched seam around a portion of the cover, so that the cover can be easily and quickly removed from the mattress for cleaning and replacement. In hospital settings, often the patients are convalescing from ailments which prevent them from caring for themselves and which causes them to soil their bedding with bodily fluids. Since cleanliness is a primary concern in this environment, mattress covers are changed often in order to allow the patient to remain comfortable and to continue to heal.
Traditionally, when a zipper is attached to the top and bottom of an envelope-like cover to provide the fastener, it has been attached by industrial sewing apparatus which generates a regular stitch line between the zipper tape and the cover material. When a zipper half is sewn to the top cover, the sewing operation generates needle holes in the mattress cover through which various thread materials are used to secure the zipper tape onto the cover. In such construction, fluids may migrate through these stitch holes, come in to contact with the mattress's, internal padding components, and contaminate the entire mattress. When this happens, the mattress may be permanently soiled by patient body fluids and other fluids that may not only propagate unpleasant odors, but may also pose a real health threat to the institution's staff and the next patient, and which may require premature mattress replacement.